Characterising different molecular landscapes in dynamic covalent networks

Lijsebetten, Filip Van; Bruycker, Kevin De; Ruymbeke, Evelyne Van; Winne, Johan M.; Prez, Filip Du

doi:10.1039/d2sc05528g

Cited by 33 publications

(51 citation statements)

References 75 publications

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“…Moreover, plotting ln(k obs ) against 1000/T in an Arrhenius plot, allowed us to determine an apparent activation energy (E a,ex ) of 77.1 ± 4.62 kJ mol −1 from the slope of the curve, which was in the same order of magnitude as previously reported dynamic systems. 50 In line with our previous investigations regarding thermal deblocking systems, 68,69 we could also identify an initial "deblocking temperature" at ∼90 °C (point at which 5% of adduct is released after 15 min) and a "half-life temperature" at ∼130 °C (point at which 50% of adduct is released after 15 min) to identify at which temperature sulfonyl isocyanate release became relatively fast. In contrast, when performing the same experiment with decyl N-phenyl carbamate (4) at 100 °C (i.e., above the deblocking temperature of SU−De), no exchange products could be determined (Figure S8).…”

Section: ■ Results and Discussionsupporting

confidence: 85%

“…Moreover, this effect became even more pronounced when increasing the relative SU content. Our research group recently published on a rheological study, where we demonstrated how these relaxation modes (i.e., macroscopic response) can be analyzed and linked to a specific reactive segment (i.e., microscopic structure) to measure reactivity changes in polymer networks . Specifically, while the single-element Maxwell model is often a good starting point (eq S4, Figure S29), using a two-element Maxwell model (eq ) is much more accurate in many cases.…”

Section: Resultsmentioning

confidence: 99%

“…As such, variations in both the modulus ( G [ T ], y -axis) and relaxation time (τ[ T ], x -axis) could be determined as a function of temperature and SU content. Distinct viscosity values (η[ T ]) could then be calculated from the Maxwell relation η[ T ] = G τ, which allowed us to make a better comparison than considering the impact on relaxation time τ[ T ] alone. , …”

Section: Resultsmentioning

confidence: 99%

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N-Sulfonyl Urethanes to Design Polyurethane Networks with Temperature-Controlled Dynamicity

et al. 2023

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Metrics & MoreArticle Recommendations * sı Supporting Information ABSTRACT: (Re)processing of cross-linked polyurethanes (PUs) is often energy intensive and inefficient since dissociation of urethane linkages at elevated temperatures generates highly reactive isocyanate moieties that can react with a wide range of nucleophiles. In this study, we first show with a small molecule study that the introduction of N-sulfonyl urethane bonds leads to dynamic covalent exchange reactions under much milder conditions compared to regular urethane groups. Then, these exchangeable N-sulfonyl urethane motifs have been introduced, in relatively small amounts (5, 10, and 20%), in a cross-linked PU matrix in an attempt to facilitate plastic flow at lower temperatures. Rheological analysis of the elastomeric dissociative networks revealed an interesting double relaxation behavior, even for temperatures between 150 and 100 °C, which could be described by a Maxwell model with two elements, which can be related to the activated and less activated urethane bonds. Finally, the (re)processability of these sulfonyl urethanes containing PUs was demonstrated through multiple cutting and hot pressing cycles and the corresponding materials showed a good retention of thermal properties.

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Section: ■ Results and Discussionsupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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N-Sulfonyl Urethanes to Design Polyurethane Networks with Temperature-Controlled Dynamicity

et al. 2023

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“…Here, lower β values indicate broader distributions of relaxation modes. Alternatively, a multielement Maxwell model may be well suited to systems with more than one type of exchange process (Figure d) . If τ* values are measured at multiple temperatures, the network flow activation energy ( E a ) is determined through the Arrhenius relationship: τ * false( T false) = A e − E a / R T where R is the ideal gas constant, T is the temperature, and A is the pre-exponential factor.…”

Section: Theories and Established Relationshipsmentioning

confidence: 99%

“…Alternatively, a multielement Maxwell model may be well suited to systems with more than one type of exchange process (Figure 7d). 80 If τ* values are measured at multiple temperatures, the network flow activation energy (E a ) is determined through the Arrhenius relationship:…”

Section: Cross-link Exchange Kinetics and Viscoelasticmentioning

confidence: 99%

Structure–Reactivity–Property Relationships in Covalent Adaptable Networks

et al. 2022

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Polymer networks built out of dynamic covalent bonds offer the potential to translate the control and tunability of chemical reactions to macroscopic physical properties. Under conditions at which these reactions occur, the topology of covalent adaptable networks (CANs) can rearrange, meaning that they can flow, self-heal, be remolded, and respond to stimuli. Materials with these properties are necessary to fields ranging from sustainability to tissue engineering; thus the conditions and time scale of network rearrangement must be compatible with the intended use. The mechanical properties of CANs are based on the thermodynamics and kinetics of their constituent bonds. Therefore, strategies are needed that connect the molecular and macroscopic worlds. In this Perspective, we analyze structure−reactivity−property relationships for several classes of CANs, illustrating both general design principles and the predictive potential of linear free energy relationships (LFERs) applied to CANs. We discuss opportunities in the field to develop quantitative structure−reactivity−property relationships and open challenges.

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Introducing Dynamic Bonds in Light‐based 3D Printing

Zhu

Houck

Spiegel

et al. 2023

Adv Funct Materials

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Light‐based 3D printing has received significant attention due to several advantages including high printing speed and resolution. Along with the development of new technologies, material design is key for the next generation of light‐based 3D printing. Conventional printable polymeric materials, also known as photopolymers or photoresins, often lead to thermosets–polymer networks cross‐linked by permanent covalent bonds which bring limited adaptability and restricted reprocessability. Dynamic bonds that can reversibly break and reform enable network rearrangement, thereby offering unprecedented properties to the materials such as adaptability, self‐healing, and recycling capabilities. Hence, introducing dynamic bonds into materials for light‐based 3D printing is a promising strategy to further expand and meet the diverse application scenarios of 3D printed multi‐functional materials and moreover meet more demanding sustainable and nature‐inspired design considerations (e.g., adaptability and self‐healing). Herein, an overview of recent advances in dynamic photopolymers for light‐based 3D printing, aiming to bridge these two promising research fields is presented. Importantly, the current challenges are also analyzed and perspectives for further developing dynamic photopolymers for light‐based 3D printing and their potential applications are provided.

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Characterising different molecular landscapes in dynamic covalent networks

Abstract: Dynamic covalent networks present a unique opportunity to exert molecular-level control on macroscopic material properties, by linking their thermal behaviour to the thermodynamics and kinetics of the underlying chemistry. Yet,...

Cited by 33 publications

References 75 publications

N-Sulfonyl Urethanes to Design Polyurethane Networks with Temperature-Controlled Dynamicity

N-Sulfonyl Urethanes to Design Polyurethane Networks with Temperature-Controlled Dynamicity

Structure–Reactivity–Property Relationships in Covalent Adaptable Networks

Introducing Dynamic Bonds in Light‐based 3D Printing

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